John ,
if you search the net - necks vs saddles.. you will find that necks tend to vary from tiny at the top of the head to large at the shoulder. These are suitable for tiny to huge dry flies
Saddles tend to be of uniform size in the top genetic product eg 14+16 or 12+14 or 16+18 with a few outside that range

If you want to tie lots of different sizes, get a neck.
If you tie commercially and want 14-16 get a suitable saddle.

The problem your friend will encounter with chinese hackle is due to import restrictions from the far east due to bird flu; and with finding consistent quality in that product. He will then have to take cream/white capes and dye them to our preference. These are generally used for salmon flies in any case, so are really not what you'd want for trout dry flies. They are however just what you would want for salmon flies and lake flies.

Genetic capes from the US have no such problem, they are easily controlled re- quality and uniformity and are generally available.
The Collins necks are a steal at that price. The quality is excellent in my view.
The grade 3 is excellent! buy one and if you don't like I'll take it off you at cost+postage.

I would forget all about the assorted dozen from ebay, you want to handle the goods or seriously trust the supplier.
Considering that - the link to Jim's custom flies as posted by Lighthouse should take you to Jim Slattery, whom you should be able to trust implicitly, as you can trust Cookshill and the products of Mr Collins and Mr Whiting.
These guys are trying to build and/or maintain a reputation, thus they want you to be happy so you return to the shop.

Enough from me, - don't spend too much
Buy a grizzly dyed golden olive, a badger and a red game/coachman neck, if these are just for you... tie some flies and do some good fishing.

All the best from an Antrim man in London,
Roy

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C & R since 1963